The invention relates to removable lids for beverage containers. More specifically, the invention relates to selectively openable push button lids for insulated beverage containers.
Thermally insulated beverage containers have become increasingly popular with the public for use with hot beverages, such as coffee. Containers of this type may also be used for cold beverages as well. Hot beverages, such as coffee and tea, impose the most demanding thermal requirements on such a container. As a result, consumers have come to appreciate that double-walled, vacuum-insulated containers perform this function best. Such containers have sidewalls often manufactured from metal, particular stainless steel, to withstand the high mechanical loading due to atmospheric pressure. Thermally insulated beverage containers designed for keeping cold beverages from becoming warm typically place a lower thermal load on the beverage container. As a result, such containers are often manufactured with a plastic double wall, wherein the interstitial space between the inner and outer walls is either thermally insulated with air or a foamed material.
In either case, it is highly desirable to provide a selectively openable lid for the beverage container. The lid performs at least two functions, the first of which is to prevent the beverage from spilling out of the container when the user is not actually drinking the beverage. This feature is particularly important when a hot beverage is in the container so as to prevent the user from becoming burned if the container tips over. As a second function, the lid should provide for drinking the fluid at a constant rate to prevent splashing or dribbling when the beverage is being drunk from the container. The lids for such containers are therefore typically provided with an open position, a closed position, and a third position in which the entire lid can be removed from the beverage container for cleaning.
Lids of this type generally fall into either the rotatable twist type lid, or the push button type lid. An example of a travel mug having a three-position, rotatable lid of the type described above is disclosed in U.S. Pat. No. 5,249,703 to Karp. That patent discloses a travel mug having two inwardly directly circumferential ears defining a gap region therebetween. A rotatable lid, having radially directed arms emanating from a central region at the bottom of the lid which adapted to pass through the gaps in the ears, and when rotated with the lid engage an underside of the circumferential rim of the lid with the radially inwardly directed ears. The rim is provided with diametrically opposed apertures to permit fluid to egress from the mug while air enters in through the remaining aperture to equalize pressure within the mug. The disclosure of this patent is incorporated herein by reference. One particular problem with this prior art design is that the drinking vessel must be specially manufactured with dedicated structure to engage the arms of the lid. In addition, although the lid is substantially splashproof when the lid is in the closed position, it is not leakproof if the mug is tipped over. Variations of the rotatable lid design are shown in U.S. Pat. No. 5,680,951 to Feltman, et al., and U.S. Pat. No. 4,190,173 to Mason, et al. These designs employ a two piece rotating structure with seals therebetween. These designs are therefore substantially more spill and leak proof than the device disclosed by Karp. Nevertheless, the two pieces are not easily separable resulting in the interstitial zones being difficult or impossible to maintain in a hygienic condition. Furthermore, almost all of the rotatable designs are difficult to operate with one hand, a serious disadvantage when using mugs having the lid and driving a car or truck.
It has become increasingly common for users to employ thermally insulated beverage containers, particularly of the type best adapted for insulating hot beverages such as coffee, in moving vehicles, such as automobiles. One design branch in the prior art has attempted to overcome the above-noted deficiencies of the twist type lid by providing a lid for such containers which is easily operated by a single hand between an open and closed position so that the user does not inadvertently spill a hot beverage on herself while driving her car. Lids of this type often employ a push bottom mechanism having a normally closed position. Examples of such prior art devices are shown in the following patents: U.S. Pat. No. 4,303,173 to Nergard; U.S. Pat. No. 3,964,631 to Albert; U.S. Pat. No. 3,967,748 to Albert; and U.S. Pat. No. 4,099,642 to Nergard. With respect to the lids disclosed in the above-identified patents, the user typically depresses a button near the rim of the lid to remove a stopper-like device from an aperture in the lid. Releasing the button returns the stopper to its normally closed position. Although devices of this type perform their intended function well, they have a significant unanticipated drawback. Specifically, the position of a stopper in a normally closed position provides an ideal breeding ground for bacteria in the junction between the stopper and the lid drinking aperture. In order to properly clean a lid of this type which quickly becomes fouled with such bacterial growth, the user must manually clean the lid by holding the mechanism open while using a brush or the like. It has been found that merely placing such lids in a dishwasher or the like will not adequately clean the area of contact between the stopper and the lid. Most users of this type of device find the requirement to manually wash the lid so inconvenient that they frequently will not purchase a second product of the same design. Furthermore, while push button lids discussed above are substantially spill proof due to the urging of the stopper like device against a value seat (typically by spring pressure), such designs are far from leak proof when used in a book bag or backpack environment.
Therefore a need exists for a splashproof and leakproof lid for an insulated beverage container which provides a truly leakproof and spillproof design in both an open and closed position, which does not encourage bacterial growth between moveable parts of the lid, which is easily cleaned by the user and which can be operated with a single hand.
It is therefore an object of the present invention to provide a removable lid for an insulated beverage container having leakproof and spillproof open and closed positions.
It is yet another object of the invention to achieve the above-described object with a removable lid which does not encourage bacterial growth between moving parts of the lid.
It is yet another object of the present invention to achieve the above objects in a removable lid which is easy to clean.
The invention achieves these objects, and other objects and advantages which will become apparent from the description which follows, by providing a selectively openable lid for a drinking vessel having a main body or base member and a rocker arm pivotally connected to an upper side of the base member. The base member has drinking and venting apertures or bores. The rocker arm carries corresponding flexible fluid seals for receipt in their respective bores such that the rocker arm is pivotable between a first, closed position and a second, open position. The fluid seals in the preferred embodiment have resilient laterally extending flanges or fingers having dimensions slightly larger than the bores to provide substantial fluid and air conduits through the respective venting and drinking bores in the base member when the rocker arm is in the second, open position, and to seal the bores in the base member when the rocker arm is in the first, closed position.
The rocker arm is preferably provided with resilient arms which are engaged with corresponding detents on the main body or base member so that the rocker arm and base member are disengagable and so that they may be cleaned by immersion in a dishwasher or the like without the need for an individual to physically maintain the members in a separate condition against spring pressure or the like.
The rocker arm and main body or base member can be provided with substantially any external geometric appearance, however a circular appearance is preferred to coincide with the substantially circular cross-sectional dimension of most beverage containers. In addition, the drinking end of the rocker arm is preferably curved and the main body is preferably provided with a depressed region surrounding the drinking aperture bore so as to form a drinking basin for the user.